The typical hard disk drive includes a head disk assembly (HDA) and a printed circuit board assembly (PCBA) attached to a disk drive base of the HDA. At least one disk is rotably mounted to the disk drive base via a spindle motor. The PCBA includes electronics and firmware for controlling the rotation of the spindle motor, controlling the angular position of an actuator that positions a head stack assembly (HSA) to which it belongs, and for providing a data transfer channel between the disk drive and its host.
During operation of the disk drive, the actuator must rotate to position head gimbal assemblies (HGAs) of the HSA adjacent desired information tracks on the disk. The actuator includes a pivot-bearing cartridge to facilitate such rotational positioning. The pivot-bearing cartridge fits into a bore in the body of the actuator. One or more actuator arms extend from the actuator body. An actuator coil is supported by the actuator body, and is disposed opposite the actuator arms. The actuator coil is configured to interact with one or more fixed magnets in the HDA, typically a pair, to form a voice coil motor (VCM).
Each HGA includes a head for reading and writing data from and to the disk. In magnetic recording applications, the head typically includes an air bearing slider and a magnetic transducer that comprises a writer and a read element. The magnetic transducer's writer may be of a longitudinal or perpendicular design, and the read element of the magnetic transducer may be inductive or magnetoresistive. In optical and magneto-optical recording applications, the head may include a minor and an objective lens for focusing laser light on to an adjacent disk surface. The head is adhered to a suspension assembly that includes a gimbal, load beam, bend region, and swage plate. The suspension acts to preload the head against the surface of the disk. The preload force is often referred to as the “gram load.” It is desirable that the gram load does not vary excessively among a population of HGAs, because the gram load affects the air bearing thickness and therefore also affects the performance of the head.
However, the gimbal or bend region of one or more suspension assemblies in a population of HGAs may be inadvertently deflected beyond its elastic limit during the handling that is associated with disk drive manufacture. Such handling damage can cause the gram load, and/or other suspension assembly characteristics that affect the air bearing (e.g., pitch static attitude, roll static attitude), to vary excessively within the population of HGAs, adversely affecting disk drive performance, manufacturing yield, and/or reliability.
In part to reduce the opportunity for handling damage, a transport or “shipping” comb is typically installed in an HSA sometime before the HSA is assembled into the disk drive. For example, often HSAs are first assembled in a different manufacturing facility than where the HDAs that incorporate such HSAs are later assembled. After the transport comb is installed in an HSA, the transport comb typically serves to protect the HSA from handling damage during transport (e.g., by preventing the heads from contacting each other). The transport comb also typically serves to separate the heads from each other enough to facilitate merging of the HSA into the disk drive during disk drive assembly (e.g., to allow the disks or ramp surfaces to merge between the heads during disk drive assembly), but not to separate the heads from each other so much that the bend areas of the suspension assemblies are thereby plastically deformed. The transport comb is then typically removed from the HSA during HDA assembly after the merging step described above.
Unfortunately, the HSA is not as well protected from handling damage before or during installation of the transport comb into the HSA. For example, the person installing a conventional transport comb into an HSA must ensure that the separator fingers of the transport comb do not rotate into contact with the suspension assemblies until the transport comb is at the correct axial position to properly separate the heads. If the person rotates the transport comb (to engage the separator fingers with the suspension assemblies) at the wrong axial position, then a separator finger may strike the side of a suspension assembly and/or deflect a suspension assembly beyond its elastic limit. Thus, there is a need in the art for a transport comb that reduces the risk of damage to an HSA during installation of the transport comb (into the HSA).